Twenty years ago, at the Democratic National Convention in Atlanta, Jesse Jackson began his historic speech by bringing Montgomery bus boycott heroine Rosa Parks up to the podium with these words: "All of us who are here think that we are seated. But we're really standing on someone's shoulders. Ladies and gentlemen, Mrs. Rosa Parks--the mother of the civil rights movement."

We should keep that thought in mind Thursday night, as we watch Barack Obama accept the nomination of the oldest political party in the world in a stadium in Denver--because Senator Obama, as he himself has often said, is also standing on lots of shoulders.

And one of those sets of shoulders belongs to Jesse Jackson.

I know what you're thinking--didn't Jackson criticize Senator Obama on Fox recently? Yes, he did, a bad mistake for which he has repeatedly apologized.

But Jackson also endorsed Senator Obama long ago, when it mattered. And over the long arc of history, Jesse Jackson's real contribution to progressive politics will include, in the words of Timothy, that he "fought the good fight...kept the faith."

Using the metaphor of the relay race, which seems appropriate with the Olympics in the background, Jackson ran his leg brilliantly, faster than anyone would have imagined when he took the baton from Dr. King four decades ago, and far closer to victory when Barack Obama picked up that same baton last year.

What do I mean? Well, consider what Jackson left on the table after his two important runs for President in 1984 and 1988:

• A Democratic Party expanded by millions of new young and African-American voters, base voters who are still helping Democrats win elections--and Barack Obama win primaries.

• The concept of the "rainbow coalition," a quilt made up of a variety of different movement patches, none of them big enough to change America unless they are sewn together into one piece.

• Rules changes, which brought the Democratic Party much closer to proportional representation, and did away with winner-take-all primaries.

When the Clinton team complained that they would be winning the 2008 primaries if they were held under Republican rules, though I found it a strange complaint to make to Democratic voters, it was also a true statement. If the two Jackson campaigns had not changed the rules, eliminating winner-take-all and "bonus" primaries, it is clear that the Obama campaign would have suffered much heavier delegate losses in states like California, New Jersey, Ohio and Pennsylvania. The delegate totals would have been much different, and slanted heavily against urban districts--which is exactly why we did away with those systems in 1988. They were not fair.

(Truth-in-advertising point: I was Jackson's national delegate coordinator in 1988, and worked on changing the party rules in the run-up to the convention.)

The point is, that Barack Obama's amazing upset victory was fashioned using rules changes that the Jackson campaigns had forced the Democratic Party to agree to two decades earlier. "Standing on someone's shoulders..."

Most important, I believe, is that the two Jackson presidential runs put flesh on the spirit of one of the civil rights movement's and Dr. King's greatest achievements--the passage of the Voting Rights Act of 1965.

The Voting Rights Act was a direct result of the march over the bridge at Selma, Alabama, the event that first brought Jesse Jackson and Dr. King together. And from their very inception, with Jesse's Southern voter registration tours in the summer of 1983, it was the two Jackson campaigns that kept Dr. King's voting rights dream alive, by dramatically expanding the African-American vote, and demonstrating the potential of the African-American vote as the base vote for Democratic victories.

Let's be clear--Democrats have not carried the white vote since 1964. To win, Democrats are dependent on an expanded "rainbow coalition," with African-American and, increasingly, Latino voters, providing the margin of victory. It will be the same this year.

Victory will come from an energized youth vote, plus an expanded grassroots vote, and by cutting our losses among whites with strong support especially from single women and union voters, and by carrying African-Americans and Latinos by huge margins. It is a strategy similar to the one we pursued in Jackson '88.

Barack Obama's team ran a brilliant primary campaign. Their upset of a strong Hillary Clinton campaign is unprecedented in modern American politics. And since Barack Obama picked up that baton, imprinted with the legacy of the civil rights movement, he has run faster and farther and smarter than anyone before him.

But when he brings tears to our eyes next Thursday night, on the forty-fifth anniversary of the March on Washington, let's not forget that he's standing on the shoulders of others--including the millions of anonymous, valiant, selfless martyrs of the civil rights movement--and a few of them more famous, including Jesse Jackson, who helped carry the baton from King to Obama.

The real point is, what we do now does matter. The struggles we fight and lose help us to win later on. The legacy of the marchers who faced down the fire hoses in Birmingham in 1963 was new voter registrations in Greensboro and Newport News and Jackson and Atlanta in 1983 and 1987, which led to a stadium in Denver in 2008--and, if we all do our part, an election in November that can help change our world.